Malignant tumors of the urinary tract can be induced in humans as a consequence of exposure to aromatic compounds to which a nitrogen atom is attached. Many compounds with similar structures have been shown to be both carcinogenic and mutagenic in experimental systems. These agents have become known as aromatic amines, because of their relationship to the first recognized compound of this class of carcinogens (e.g. 2- naphthylamine, 4-aminobiphenyl, benzidine, etc.). The goals of research on these compounds have been to evaluate the extent of exposure, to determine their mechanisms of action and to identify means by which carcinogenic effects in humans might be circumvented. These efforts have in common the chemical nature of these chemicals, their metabolic disposition in biological systems and their abilities to induce mutations and tumors in a wide variety of organisms. Their inadvertent formation in the environment and the desirable properties that make many of them economically important have tended to stimulate research in diverse settings, including industry, government and academia. The purpose of this application is to obtain partial support for the Third International Conference and Mutagenic N-Substituted Aryl Compounds. The objective of the conference would be to promote the multidisciplinary interchange of methodologies, experimental approaches, data and research opportunities among the world's scientists who ar involved in studies of this class of compounds. The first two conferences, held in Washington, D.C. in 1979 and Hot Springs, Arkansas in 1982, established a mechanism for such an exchange that is unique in the area of aromatic amines; we feel that a third conference would build on these beginnings and be even more effective in providing practical solutions to common problems.